West Valley City, Utah -- After 3 1/2 years of searching in 11 states, the hunt for Susan Powell has been called off.
The end of the search for the missing mom was announced during a news conference Monday afternoon by West Valley City manager Wayne Pyle. He said police will release the "voluminous" documents produced by the investigation, some of which had previously been sealed by court order.
Powell was last seen on Dec. 6, 2009, at her West Valley City home, which she shared with her husband, Josh Powell, the only person of interest ever named in the case.
Josh Powell claimed he left his wife at home as he took his sons, then ages 4 and 2, on a late-night camping trip in desert of west Utah. He denied having anything to do with his wife's disappearance.
Josh Powell killed himself and the couple's sons last year when he set fire to their rented home in Washington.
Deputy Chief Mike Powell (no relation to Josh Powell) said Monday that the investigation involved talking to hundreds of people and following up on more than 800 tips. Some of the newly-released documents were sealed to "protect the integrity of the investigation." However, Mike Powell said Monday that "successful prosecution was not likely to happen at this point."
"We have left no stone unturned during the last 3 1/2 years of this investigation," he added.
Mike Powell said during the news conference that investigators believed "early on" that Josh Powell was involved in his wife's disappearance.
Investigators and a deputy district attorney treated the case as a homicide and kidnapping.
Among other things, investigators obtained a wiretap order, which they used to monitor communication between Josh Powell and his brother Michael. The wiretapping began in August 2011 and continued until October. Police also used dogs, underwater search tools, aircraft and other means to look for Susan.
Deputy Chief Powell said during the news conference that after Josh's death investigators turned their attention to Michael Powell. Investigators believed Michael may have transported Susan's body shortly after her disappearance.
Michael and Josh also used sophisticated computer encryption to communicate, according to West Valley City Deputy Chief Phil Quinlan. Investigators have been unable to decipher that encrypted communication, Quinlan added.
Michael Powell committed suicide in February of this year by leaping from a building in Minneapolis, where he lived. That left investigators without any person of interest in the case.
At the time of his death, Michael Powell was embroiled in a legal battle in U.S. District Court for Western Washington with Susan's parents, Chuck and Judy Cox, over $1.5 million in insurance policies issued to Josh Powell and sons Charlie, 7, and Braden, 5.
About four months before his death, Josh Powell changed his policy to list Michael Powell, rather than his wife and a family trust, as the primary beneficiary. Michael Powell was to receive a 93 percent share, with 4 percent left to Alina Powell and 3 percent to brother John. In the event of Michael's death, the proceeds were to be split equally between Josh and Michael's sister, Alina Powell, and their father.
Police considered that suspicious, Mike Powell said.
The deputy chief also said Monday that the brothers' father, Steve Powell, was not directly involved in Susan's disappearance but may have learned of it afterward. However, he has not been forthcoming with investigators.
"He is entirely uncooperative and wants nothing to do with law enforcement," Mike Powell said.
Steve Powell currently is serving a prison sentence for a conviction on voyeurism charges. He could be eligible for release later this month.
The search for Susan Powell most recently took investigators to a home in rural Scotts Mills, Ore. The house had been rented by Josh Powell's aunt and uncle at the time of Susan Powell's disappearance. The search was called off after two days when nothing was found.